1. Field of the Invention.
This invention relates to the control of fluid-spraying devices and more particularly to the control of fluid scaling and cleaning devices having a return to supply from the outlet.
2. Description of the Prior Art.
The discharging from a very high pressure hydraulic system is often employed in cleaning and scaling operations. Fluids under very high pressure are difficult to control and hazardous if not properly controlled.
Before my invention, very high pressure hydraulic systems used in cleaning and scaling operations included the use of a supply reservoir containing liquid, a high pressure pump, a control valve mounted on the outlet of the high pressure pump and a discharge device connected to the control valve. By means of an electric switch mounted on the discharge device, the control valve could be operated to direct the flow of high pressure liquid through the discharge device or to bypass the flow of high pressure liquid back into the supply reservoir.
If the system of electric power to control valve failed, then the system would, in at least some circumstances, continue to discharge liquid under high pressure. This presented a hazard to operation personnel.
Applicant was aware of the following U.S. patents:
______________________________________ Goss 3,147,767 239/130 Stasz 3,380,658 239/127 Tuttle 3,690,558 239/127 Manor 3,910,497 ______________________________________